/Engine/Plugins/Experimental/AnimNext/Source/AnimNext/Public/GenerationTools.h
Utility for taking two arrays of bone indices, which must be strictly increasing, and finding the A - B. That is - any items left in A, after removing B.
static void DifferenceBoneIndexArrays ( const [TArray](API\Runtime\Core\Containers\TArray)< FBoneIndexType > & A, const [TArray](API\Runtime\Core\Containers\TArray)< FBoneIndexType > & B, [TArray](API\Runtime\Core\Containers\TArray)< FBoneIndexType > & Output )